The object of the invention is a multi-layered transportation and storage container for the long time storage of radioactive wastes, especially from spent fuel elements, in suitable geological formations.
Irradiated, spent fuel elements after a temporary storage in water basins are either immediately or after a limited further intermediate storage worked up. Thereby, the nuclear fuel and fissile material of the fission products are separated and again supplied to the fuel cycle. The fission products according to known processes are conditioned, mostly using large amounts of valuable materials, as for example, lead and copper and are final stored in no longer removable manner in suitable geological formations.
Furthermore, there has been proposed (report of the Kernforschungszentrum Karlsruhe KFK 2535 and 2650) not working up the irradiated fuel elements in foreseeable time, to first give up the fuel and fissile materials in them and, after a suitable decay time in storehouses provided therefore, in a given case to again final store the fuel elements in non-removable manner. The storage time can range from several generations to several thousand years, whereby the potential danger of the radioactive inventory according to the known laws of physics in this time, depending on its composition, is extraordinarily greatly reduced.
Because of the undetermined storage time, there are placed especial requirements on such containers suited for the long time storage, which containers compared to known transportation and storage containers must have a much longer service life. Increasing the difficulty is the fact that the container storage must be accessible only with difficulty, and consequently limits are placed on the possibility of supervision.
There are known concepts which in part are very expensive for storing the irradiated fuel elements by means of containers made of metal or concrete in salt, sand, or in rock caves.
As packaging material for radioactive materials and irradiated fuel elements, there have been proposed containers made of alloyed and unalloyed steels, of copper as well as of corundum. The containers of steel are either not sufficiently resistant to corrosion or like those of copper are very expensive. Containers of corundum are basically suitable, but there is lacking the necessary experience for this production. Furthermore, the fuel elements for the packaging must be split up into small corundum containers for reasons of production which involves a considerable expense.
Such containers only partially fulfill the conditions of long time storage, such as tight sealing at the pressures and temperatures which occur, as well as corrosion-resistance against salt liquors, or they must be constructed with very thick walls. Besides, for the most part, they are not suited also simultaneously to be used as transportation containers so that there must take place a reloading of the waste from transportation containers into the final storage container.
Therefore, it was the problem of the present invention to provide a multi-layered transportation and storage container for the long time storage of radioactive wastes, especially from spent fuel elements, in suitable geological formation which guarantees a tight sealing even for a long period of time and above all is corrosion resistant to salt liquors without being too expensive and too heavy.